There's a time limit to how long development advocates can frame their crusade in terms of national security. The reason the national security lens gets any purchase at all is because of fragile states, and fragile states only because of Afghanistan.
If support for war in Afghanistan is deteriorating, how long before the tide shifts back against looking at development as a national security priority? And that narrative in turn becomes subsumed in a neo-realist perspective that frames attempts to stabilize fragile states as filled w/ hubris?
Afghanistan's chief challenge is governance, a sector the military seems more disposed to address than the development community. If State and USAID are unable to seriously address the core problems of fragile states, when this narrow window of opportunity closes Congress will see the additional resources they've invested in State and USAID as wasted. Is that unfair? Perhaps, but that's how it is.